This invention relates to a disposable body fluids absorbent article such as a sanitary napkin or a disposable diaper and more particularly to such an article including a liquid-pervious topsheet formed with a plurality of pleats.
Japanese Patent Application Disclosure Gazette (Kokai) No. Hei7-328061 discloses a sanitary napkin in which a liquid-pervious topsheet is made of a nonwoven fabric formed with a plurality of high density zones and low density zones alternately arranged in a stripe-pattern. The high density zones have their upper surface covered with plastic film. The low density zones are protuberant relatively to the upper surface of the high density zones.
The topsheet of the napkin allows menstrual fluid to spread rapidly toward longitudinally opposite ends of the napkin along the high density zones extending in the stripe-pattern after menstrual fluid has transferred from the low density zones to the high density zones. Accordingly, the napkin allows an absorption capacity of a body fluids absorbent core to be efficiently utilized not only in a central region of the napkin on which menstrual fluid is discharged but also in the longitudinally opposite ends of the napkin.
With the known napkin, the presence of the high density zones enables the absorption capacity of the napkin to be efficiently utilized also in the longitudinally opposite ends thereof. However, the high density zones covered with the plastic film can not directly absorb menstrual fluid and, as a result, a rate of menstrual fluid absorption can not be improved as much as expected from a large surface area of the topsheet.
It is an object of the present invention to utilize an absorption capacity of a disposable body fluids absorbent article such as a sanitary napkin as efficiently as possible without deteriorating a rate of body fluids absorption.
According to the present invention, there is provided a disposable body fluids absorbent article including a body fluids absorbent core having a surface thereof at least partially covered with a liquid-pervious sheet of nonwoven fabric, the nonwoven fabric being partially formed with a plurality of alternately arranged high density zones and low density zones extending substantially in one direction. The topsheet is formed by thermoplastic synthetic fibers having a basis weight of 20xcx9c80 g/m2 and formed with a plurality of pleats extending in the one direction, the pleats repeating undulation transversely of the one direction, the high density zones being defined by crests and troughs of the pleats and the low density zones being defined between the crests and troughs, and the troughs being in contact with a surface of the absorbent core.
According to one embodiment of the present invention, a depth from the crest to the trough of the pleat is 1xcx9c10 mm and a distance between each pair of adjacent crests is 1xcx9c15 mm.
According to another embodiment of the present invention, a density of the high density zone is 0.08xcx9c0.25 g/cm3.
According to still another embodiment of the present invention, a width of the high density zone is 0.5xcx9c3 mm.
According to further another embodiment of the present invention, the high density zones continuously extend in the one direction.
According to an additional embodiment of the present invention, the high density zones intermittently extend in the one direction.